1. Field of the Invention
This invention concerns a tire/wheel assembly assembling method, a tire/wheel assembly assembling line, a wheel, and a wheel manufacturing method, which improve the working efficiency in assembling together a tire and a wheel and improve the outer appearance of the wheel.
2. Description of the Related Art
A tire/wheel assembly (car wheel) used in an automobile or other vehicle is comprised of a wheel and a tire, which is assembled onto the wheel. The wheel has an annular rim, onto which the tire is assembled, and a disk, which is welded to the rim and to which the hub of the shaft of a vehicle is fixed by means of bolts, etc.
Such wheels and tires are non-uniform in weight, dimensions, rigidity, etc. due to the scattering that occurs in the respective manufacturing processes. The uniformity of weight is referred to as balance. The condition in which balance is not achieved is called unbalance, and there is static unbalance and dynamic unbalance. Static unbalance refers to the non-uniformity of weight distribution that exists in the circumferential direction in the still condition and causes vibration of the car body in the vertical direction. Dynamic unbalance refers to the non-uniformity of weight distribution that exists in the rotating condition and causes vibration of the car body in the vertical and lateral directions as well as steering shimmy. The uniformity of the dimensions is referred to as xe2x80x9crunoutxe2x80x9d, and there is radial runout (referred to hereinafter as xe2x80x9cRROxe2x80x9d), which is the runout in the radial direction (vertical runout), and lateral runout, which is the runout in the width direction (lateral runout). The uniformity of rigidity is referred to as xe2x80x9cforce variationxe2x80x9d, and there is radial force variation (referred to herein after as xe2x80x9cRFOxe2x80x9d), which is the variation of force in the radial direction, and lateral force variation, which is the variation of force in the width direction. Among these characteristics, a large unbalance and RFV in particular cause vibration of a vehicle. The unbalance and RFV must thus be lessened.
Balance in the direction around the rotation axis and in the direction of the rotation axis must thus be achieved with a tire/wheel assembly, in which a tire and a wheel are assembled together. However, if a wheel and tire are assembled together without consideration of the abovementioned static balance of the wheel and tire, unbalance in the direction around the rotation axis and in the direction of the rotation axis will occur. The condition in which the balance in the direction around the rotation axis is not achieved is static unbalance, and if static balance is not achieved, vibration in the vertical direction will occur during travel. The condition in which the balance in the direction of the rotation axis is not achieved is dynamic unbalance, and if dynamic balance is not achieved, vibration in the vertical and lateral directions will occur and cause steering shimmy, etc.
Since non-uniformity exists in the wheel alone and the tire alone as described above, in order to lessen the non-uniformity, the non-uniformity of the tire/wheel assembly, with which the wheel and tire are assembled together, is lessened as much as possible. Various methods are thus employed as methods of assembling a tire/wheel assembly. Two representative assembling methods shall be described below.
As a first method, there is the method of reducing the RFV of the tire/wheel assembly. With this method, a tire and a wheel are assembled together upon performing phase matching of the maximum point of the RFV of the tire with the minimum point of the RRO (so-called low point) of the wheel. By this assembling method, the tire/wheel assembly as a whole is made to approach a circular shape and the vibration in the vertical direction during the rotation of the tire/wheel assembly is reduced. Here, if the light point of the tire, which is the lightest part in the weight distribution in the circumferential direction of the tire, and the heavy point of the wheel, which is the heaviest part in the weight distribution in the circumferential direction of the wheel, are at mutually close positions, the static unbalance of the tire and the static unbalance of the wheel cancel each other out to lessen the static unbalance of the tire/wheel assembly as a whole. However, if assembly is performed with priority given to matching the direction of the maximum point of the RFV of the tire with the direction of the minimum point of RRO of the wheel as mentioned above, the light point of the tire and the heavy point of the wheel will normally not be matched and balance weights must be added further.
Thus in order to determine the weight and position of attachment of the balance weights after assembly, the tire/wheel assembly is set on an unbalance measuring device (referred to hereinafter as a xe2x80x9cbalancerxe2x80x9d) and the weight and position (angle) of the unbalance of the tire/wheel assembly are measured. After measurement, balance weights (lead, etc.), which correspond to the weight of the unbalance, are attached to the rim of the wheel at locations corresponding to the position of the unbalance to adjust the balance, and the measurement of unbalance and adjustment of the balance weights are repeated until the amount of unbalance becomes less than or equal to a fixed amount. In order to improve the efficiency of the balance weight attachment work, the position of attachment of the air valve, which becomes the heavy point, is used as a guide-line for the attachment position of the balance weights. Balance weights are normally attached at two locations at the outer side and the inner side of the wheel.
A second method is the method of lessening the unbalance of the tire/wheel assembly. With this method, the tire and wheel are assembled together upon performing phase matching of the light point of the static unbalance of the tire and the heavy point of the static unbalance of the wheel. By this assembly, the static unbalances of both the tire and wheel cancel each other out so that the static unbalance of the tire/wheel assembly as a whole is lessened and the vibration in the vertical direction during travel can be restrained. After assembly, the RFV is improved using a tire fitter. Furthermore, if unbalance still remains in the tire/wheel assembly, the weight and position (angle) of the unbalance of the tire/wheel assembly are measured using a balancer in order to lessen the unbalance. Balance weights, corresponding to the weight of the unbalance, are then attached to the rim of the wheel at locations corresponding to the unbalance.
In particular with this method, since an air valve for supplying compressed air into the tire is attached to the rim of the wheel, the weight of this air valve is taken into account and the air valve attachment position is used as the heavy point of the wheel in many cases. Thus in this case, the light point of the static unbalance of the tire is phase matched with the air valve attachment position of the wheel.
As has been described above, with both methods, the setting of the heavy point of the static unbalance of the wheel to the air valve attachment position is effective in providing a guideline for assembly that can be judged readily. However, since the weight of an air valve is not so high, in the case where the scattering of the weight distribution is large among the respective products due to manufacturing errors of the wheel body, this scattering may override the weight of the air valve and the heavy point of the wheel as a whole may not necessarily coincide with the air valve attachment position. In relation to this problem, Japanese Unexamined Patent Publication No. 2000-170843 discloses an invention of a method for making the heavy point of the static unbalance of the wheel coincident with the air valve attachment position. With this invention, for each of the members, which comprise the air valve, for example, the air valve body, the cap that covers the air inlet of the air valve, etc., a plurality of types that differ in weight are prepared in advance and the weight of the air valve itself is adjusted by selectively attaching members with appropriate weights to forcibly make the heavy point coincide with the air valve attachment position.
The casing structure of an air valve and the attachment of an air valve to a wheel shall now be described with reference to FIG. 31. FIG. 31 is a diagram, which shows the rim of a wheel and the casing structure of an air valve. The structure of the air path, etc. inside the air valve are omitted. In FIG. 31, the casing of air-valve 201 is comprised of a substantially cylindrical stem part 201a and a grommet part 201b, which is formed across a fitting groove 201c provided along the circumferential direction at one end of stem part 201a. An air inlet 201d is formed at the other end of stem part 201a and a cap 201e is attached so as to cover this air inlet 201d. Also, the surface of air valve 201 is normally covered with a synthetic rubber material. Air valve 201 is attached to the rim 200a of a wheel 200 by insertion, by making use of the resilience force of rubber, of the stem part 201a into a circular air valve attachment hole 200b, formed in rim 200a, from the side at which the tire is fitted, fitting the fitting groove 201c to the circumferential surface of air valve attachment hole 200b, and stopping grommet part 201b onto rim 200a. The stem part 201a is thus pushed into air valve attachment hole 200b in the attachment of air valve 201, and in order to prevent cutting and flawing of the surface of air valve 201, which is comprised of synthetic rubber material, the outer and inner circumferential edge parts 200c of air valve attachment hole 200b is subject to burr removal and other forms of so-called xe2x80x9cedge treatmentxe2x80x9d in advance, and normally, cutting of the edge is performed using a machine tool, etc. However, since wheel 200 is a large part, a wide occupied space had to be secured for the edge treatment process, and since as can be understood from FIG. 31, air valve attachment hole 200b is made within a narrow step formed on rim 200a, the cutting by a machine tool for edge treatment was difficult and required special tools and jigs.
The problems of the above-described two assembly methods shall now be described.
With the first of the above-described methods, though the RFV is lessened after assembly of the tire and wheel, since there is no correlation between the static unbalance and the RRO of the wheel, a large unbalance remains in the weight distribution of the tire/wheel assembly. Large balance weights must thus be attached to the wheel in order to lessen this unbalance. As a result the large balance weights cause the manufacturing cost to increase and the outer appearance of the tire/wheel assembly to become poor, thus causing the commercial value to drop, etc.
With the second of the above-described methods, though the unbalance is lessened after assembly of the tire and the wheel, since there is no correlation between the static unbalance and the RRO of the wheel, a large RFV remains and causes vibration during travel. This RFV must thus be lessened by use of a tire fitter, etc. Furthermore, though the balance weights to be attached will be smaller with this second method, since balance weights still have to be attached, the problem of outer appearance still remains. Especially in the case where the heavy point of the static unbalance of the wheel is set to the air valve attachment position, since the heavy point will not necessarily coincide with the air valve attachment position, an unbalance will remain in the weight distribution of the tire/wheel assembly.
A plurality of types that differ in weight must thus be prepared as mentioned above for the members that comprise the air valve in order to forcibly make the heavy point of static unbalance coincide with the air valve attachment position. In this case, there will be problems in terms of economy and control of parts, and due to the trouble of having to select members of appropriate weights for each tire/wheel assembly, there is also a problem in terms of efficiency of the balance adjustment work. It is therefore desirable to be able to make the heavy point of static unbalance coincide with the air valve attachment position using just standard specification items and without having to prepare a plurality of types of air valves according to weight. It is also preferable with regard to the air valve attachment hole to enable omission or simplification of the edge treatment process.
Moreover, with the above-described two assembly methods, the weight and position of unbalance of the tire/wheel assembly must be measured using a balancer in order to attach balance weights after assembly of the tire and wheel. The balance adjustment work thus becomes a troublesome work with many processes, requires extremely many manhours, and is poor in working efficiency. It is therefore desirable for the balance weights to be as small as possible and for balance weights not to be attached where possible, and in the case where balance weights must be attached, it is desirable to be able to specify the attachment locations without having to measure the balance.
In the case of aluminum wheels, since a balance weight is attached to the inner circumferential side of the rim of a wheel, there is also the problem that the clearance between the balance weight and the brake device becomes small.
An object of this invention is therefore to resolve the above problems by providing a tire/wheel assembly assembling method, a tire/wheel assembly assembling line, a wheel, and a wheel manufacturing method, which improve the working efficiency in the assembling of a tire and a wheel and improve the outer appearance of the wheel.
(1) This invention provides a tire/wheel assembly assembling method, which is a method of assembling a tire/wheel assembly with which a tire and a wheel are assembled together, and is comprised of a balance weight determination step, in which the weight and attachment position of a balance weight to be attached to the abovementioned wheel are determined on the assumption that the minimum point of the RRO of the abovementioned wheel will be phase matched with the maximum point of the RFV of the abovementioned tire and based on the weight and position of the heavy point of the static unbalance of the abovementioned wheel and the weight and position of the light point of the static unbalance of the abovementioned tire, a balance weight attachment step, in which a balance weight of the weight determined in the abovementioned balance weight determination step is attached to the attachment position of the abovementioned wheel that was determined in the abovementioned balance weight determination step, and an assembling step, in which the abovementioned wheel and the abovementioned tire are assembled together upon phase matching the minimum point of the RRO of the abovementioned wheel with the maximum point of the RFV of the abovementioned tire.
With this tire/wheel assembly assembling method, by phase matching of the minimum point of the RRO of the wheel and the maximum point of the RFV of the tire, the large force in the radial direction of the tire is absorbed by dimensional variations in the radial direction of the wheel. Furthermore with this method, by attachment of a balance weight to the wheel in the balance weight attachment step, the unbalance of the tire/wheel assembly is lessened. Also with this method, a balance weight can be mounted, based on the weight and position of the balance weight determined in the balance weight determination step, to the outer circumferential surface of the rim of the wheel prior to assembling the wheel and the tire together, and when the balance weight is attached at such a position, the balance weight will be covered by the tire in the tire/wheel assembly.
This invention also provides a tire/wheel assembly assembling line, which is an assembling line for a tire/wheel assembly, with which a tire and wheel are assembled together, and is comprised of a wheel marking process, in which the minimum point of the RRO of the abovementioned wheel is marked, a tire marking process, in which the maximum point of the RFV of the abovementioned tire is marked, a balance weight determination process, in which the weight and attachment position of a balance weight to be attached to the abovementioned wheel are determined on the assumption that the minimum point of the RRO of the abovementioned wheel will be phase matched with the maximum point of the RFV of the abovementioned tire and based on the weight and position of the heavy point of the static unbalance of the abovementioned wheel and the weight and position of the light point of the static unbalance of the abovementioned tire, a balance weight attachment process, in which a balance weight of the weight determined in the abovementioned balance weight determination process is attached to the attachment position of the abovementioned wheel that was determined in the abovementioned balance weight determination process, and an assembling process, in which the abovementioned wheel and the abovementioned tire are assembled together upon phase matching the abovementioned marked position of the wheel with the abovementioned marked position of the tire.
With this tire/wheel assembly assembling line, by phase matching of the minimum point of the RRO of the wheel with the maximum point of the RFV of the tire in the assembling process, the RFV of the tire/wheel assembly is lessened. Furthermore with this assembling line, by attachment of a balance weight to the wheel in the balance-weight attachment process, the unbalance of the tire/wheel assembly is lessened, and the unbalance measurement process and balance weight attachment process subsequent assembly are eliminated. Also with this assembling line, since a balance weight can be mounted, based on the weight and position of the balance weight determined in the balance weight determination process, to the wheel in the balance weight attachment process prior to the assembling process, the balance weight can be mounted at the outer circumferential surface of the rim of the wheel, which becomes covered by the tire after the assembling process.
Phase matching refers to the matching of the direction of a predetermined point along the circumferential direction of the tire with the direction of a predetermined point in the circumferential direction of the wheel with the centers of the tire and the wheel being matched.
(2) This invention also provides a wheel, which is adjusted in balance in accordance to a tire, based on the three data of the unbalance amount xe2x88x92g of the light point of the abovementioned tire, the maximum RRO amount +xcex4 of the abovementioned tire, and the phase xcex8 from the abovementioned light point to the direction of the abovementioned RRO amount +xcex4, and which is characterized in that the phase from the heavy point of the abovementioned wheel to the direction of the minimum point of the RRO of the abovementioned wheel is xcex8, the minimum RRO amount of the abovementioned wheel is xe2x88x92xcex4, and the unbalance amount of the abovementioned heavy point is +g.
This invention also provides a tire/wheel assembly assembling method, which is a method of assembling the abovementioned balance-adjusted wheel and the abovementioned tire together and is characterized in that the assembly is performed to make the abovementioned light point and the abovementioned heavy point be of the same phase.
With such a wheel and tire/wheel assembly assembling method, by assembling so that the light point of the tire and the heavy point of the wheel are matched, the unbalance amount xe2x88x92g of the light point and the unbalance amount +g of the heavy point are canceled out so that the static unbalance will be substantially eliminated. Also, the RRO amount +xcex4 of the tire at a position that is shifted in phase from the light point by the amount xcex8 and the RRO amount xe2x88x92xcex4 of the minimum point of the wheel at a position that is shifted in phase from the heavy point by the amount xcex8 are made the same in phase and thus made to cancel each other out so that the vertical runout of the tire/wheel assembly as a whole will be made small. The static unbalance can thus be minimized while minimizing the vertical runout in the condition where the tire and wheel are assembled together even if the static balance is not adjusted afterwards by use of a balance weight.
That the unbalance amount of the heavy point of the wheel is +g shall mean that the unbalance amount of the heavy point is +g in the condition where an air valve has been attached.
Also, the amounts of +g and xe2x88x92g and +xcex4 and xe2x88x92xcex4, etc. do not have to be matched strictly and may differ slightly within a range in which the tire/wheel assembly will be satisfactory as a product.
This invention also provides a wheel manufacturing method, which is a method of manufacturing a wheel that is adjusted in balance in accordance to a tire, based on the three data of the unbalance amount xe2x88x92g of the light point of the abovementioned tire, the maximum RRO amount +xcex4 of the abovementioned tire, and the phase xcex8 from the abovementioned light point to the direction of the abovementioned RRO amount +xcex4, and which is characterized in that after measurement of the minimum point of the RRO of the wheel, a trimming process is performed on the wheel so that the heavy point, with an unbalance amount of +g, is positioned in the direction that is shifted by xe2x88x92xcex8 in phase with respect to the measured minimum point of RRO.
With a wheel obtained by this manufacturing method, by performing assembly upon matching the light point of a tire with the heavy point of the wheel, the unbalance amount xe2x88x92g of the light point and unbalance amount +g of the heavy point are made to cancel each other out, thereby substantially eliminating the static unbalance. Also, the maximum point of RRO of the tire at a position that is shifted in phase from the light point by the amount xcex8 and the minimum point of RRO of the wheel at a position that is shifted in phase from the heavy point by the amount xcex8 are made the same in phase and thus made to cancel each other out so that the vertical runout of the tire/wheel assembly as a whole will be made small. The static unbalance can thus be minimized while minimizing the vertical runout in the condition where the tire and wheel are assembled together even if the static balance is not adjusted afterwards by use of a balance weight.
This invention also provides a wheel manufacturing method, which is a method of manufacturing a wheel that is adjusted in balance in accordance to a tire, based on the three data of the unbalance amount xe2x88x92g of the light point of the abovementioned tire, the maximum RRO amount +xcex4 of the abovementioned tire, and the phase xcex8 from the abovementioned light point to the direction of the abovementioned RRO amount +d , and which is characterized in that after cutting of the outer circumference of the wheel in a decentering manner such that the minimum RRO amount of the wheel will be xe2x88x92xcex4, a trimming process is performed on the wheel so that the heavy point with an unbalance of +g, will be positioned in the direction that is shifted by xe2x88x92xcex8 in phase with respect to the minimum point of RRO of the abovementioned wheel.
A wheel that is obtained by this manufacturing method can be made a wheel with which the minimum point of RRO, that is, the minimum point of the vertical runout amount, is matched with the vertical runout of the tire and the measurement of the minimum point of RRO of the wheel is unnecessary. Also, by performing assembly upon matching the light point of the tire with the heavy point of the wheel, the unbalance amount xe2x88x92g of the light point and the unbalance amount +g of the heavy point are made to cancel each other out, thereby substantially eliminating the static unbalance. Also, the RRO amount +xcex4 of the tire at a position that is shifted in phase from the light point by the amount xcex8 and the RRO amount xe2x88x92xcex4 of the minimum point of the wheel at a position that is shifted in phase from the heavy point by the amount xcex8 are made the same in phase and thus made to cancel each other out so that the vertical runout of the tire/wheel assembly as a whole will be made small. The static unbalance can thus be minimized while minimizing the vertical runout in the condition where the tire and wheel are assembled together even if the static balance is not adjusted afterwards by use of a balance weight.
Furthermore, in an above-described wheel manufacturing method, an air valve attachment hole may be bored in the direction that is shifted in phase by xe2x88x92xcex8 from the abovementioned minimum point of RRO of the wheel.
With a wheel obtained by this manufacturing method, since the heavy point of the wheel will be in the direction of the air valve attachment hole, a worker who assembles a tire and a wheel together can eliminate the static unbalance in the condition where the tire and wheel are assembled simply by performing assembly upon matching the air valve and the light point of the tire by using the air valve as a guideline of the heavy point, and since the maximum point of RRO of the tire and the minimum point of RRO of the wheel are made the same in phase and thus made to cancel each other out, the static unbalance can be minimized while minimizing the vertical runout in the condition where the tire and wheel are assembled together.
Here, phase shall refer to the angle formed by two directions that are directed from the center of a tire or wheel to the positions of two predetermined points along the circumference, side surface, etc. of the tire or wheel.
Also with the above-described wheel manufacturing method, setting the unbalance amount equal to +g shall mean that the unbalance amount is set equal to +g in the condition where an air valve is attached to the wheel.
Also, since the phases of the primary peaks of the RRO and RFV of a tire are highly correlated, the manufacturing of a wheel using the maximum point of RRO of the tire as a guideline is equivalent to practicing the above-described manufacturing method using the position of the primary peak of RFV as a guideline.
(3) This invention also provides in a wheel, which is formed by joining a rim and a cup-like disk, which is fitted to the inner diameter of the abovementioned rim, a wheel with which the balance is adjusted by the provision of trimmed shape and/or augmented shapes at the fitting part of the abovementioned cup-like disk.
With this wheel, since the disk will be light in the direction in which the trimmed shapes are provided, a wheel of the desired balance can be made by providing trimmed shapes of the desired amount. Moreover, since a part of the disk that will be fitted to the inner surface of the rim and will be hidden from the exterior will be trimmed or augmented to adjust the balance, a wheel that is adjusted to the desired balance can be made without affecting the outer appearance of the wheel.
Since an air valve for putting air into a tire will be attached to the rim of a wheel, the rim will tend to be heavy in the direction of the air valve. The balance of the wheel and air valve as a whole must thus be adjusted in consideration of the contribution of the air valve and air valve attachment hole to the weight balance.
This invention also provides in a wheel, which is formed by joining a rim and a cup-like disk, which is fitted to the inner diameter of the abovementioned rim, a wheel with which the balance is adjusted by making the direction, as viewed from the center of the abovementioned disk, of the air valve attachment hole provided in the abovementioned rim be matched with the direction of trimmed shapes provided at the fitting part of the abovementioned disk or by making the abovementioned direction of the air valve attachment hole be shifted by 180 degrees with respect to the direction of augmented shapes provided at the fitting part of the abovementioned disk.
With this wheel, since the unbalance due to the weight of the air valve and the unbalance due to the trimmed shapes or augmented shapes cancel each other out, the unbalance of the wheel as a whole can be made to approach zero. As a result, a balance weight to be attached after assembly with the tire can be made small to thereby improve the outer appearance of the wheel.
This invention also provides in a wheel, which is formed by joining a rim and a cup-like disk, which is fitted to the inner diameter of the abovementioned rim, a wheel with which the balance is adjusted by making the direction, as viewed from the center of the abovementioned disk, of the air valve attachment hole provided in the abovementioned rim be shifted by 180 degrees with respect to the direction of trimmed shapes provided at the fitting part of the abovementioned disk or by making the abovementioned direction of the air valve attachment hole be matched with the direction of augmented shapes provided at the fitting part of the abovementioned disk.
With this wheel, since the air valve direction is made relatively heavy by the joint effect of the unbalance due to the air valve attached to the rim and the unbalance due to the trimmed shapes or augmented shapes, the heavy point of the wheel can always be set in the direction of the air valve. The direction of the air valve can thus be used as a guideline for the heavy point of the wheel, enabling the work of adding a balance weight to be made efficient.
Here, joining may be performed by any method by which the rim and disk can be joined without damaging the function of the wheel, and various known methods, for example, welding, brazing, bolting, adhesion by adhesive agent, etc., may be used.
(4) This invention also provides a wheel with which an annular air valve seat is fitted and fixed inside an air valve attachment hole, which has been bored in the rim, and an air valve is attached to the abovementioned air valve seat.
With this wheel, edge treatment can be performed according to each air valve seat and the occupied space required for the edge treatment process can be reduced. Simplification or omission of the edge treatment is also enabled.
Furthermore, the abovementioned air valve seat of the above-described wheel may be arranged from a material that is greater in specific gravity than the material of the main body of the wheel.
With such a wheel, the heavy point of the static unbalance of the wheel can be matched with the air valve attachment position, and since the air valve can be arranged from just standard specification items, the wheel will be more economical and excellent in the efficiency of adjustment work in comparison to the case where the weight of the air valve itself is adjusted as in the prior art.
(5) This invention also provides a wheel characterized in that augmented shapes or trimmed shapes, corresponding to a predetermined weight, are provided in a localized manner when the wheel is in the condition of a net-shape part in the manufacturing process and the adjustment of the weight balance is enabled by these augmented shapes or trimmed shapes.
With this wheel, a wheel that has the desired weight balance can be made, without damaging the outer appearance, simply by partial design changes of the mold that is used to manufacture the wheel. In particular, it becomes possible to match the heavy point of the static unbalance with the air valve attachment position without fail even in the case where the scattering of the weight distribution is large among the respective products due to manufacturing errors, etc. of the wheel. The weight balance adjustment process of the tire/wheel assembly can thus be simplified.
(6) This invention also provides in a wheel, comprised of a circular disk, which can be fixed to the hub of the shaft of a vehicle, and a rim, which is fixed to the peripheral part of the disk and onto which a tire is assembled, a wheel having an arrangement wherein the balance is adjusted by providing the disk with openings for setting the heavy point position of the abovementioned wheel at a position away from the center of the abovementioned disk.
With this wheel, openings are formed in the disk to enable the setting of the heavy point position of the wheel at a predetermined position by adjustment of the sizes, positioning intervals, etc. of the openings. Since the checking work, etc. of the heavy point of the wheel in the assembling of the tire/wheel assembly can thus be simplified, the working efficiency of the balance adjustment work can be improved. Also, though when openings are formed, the weight of the disk will be reduced by the amount corresponding to the sizes of the openings, in the case where the openings are made at equal intervals in the circumferential direction of the disk, the weight balance of the disk will not change since the weight reductions due to the respective openings will cancel each other out. However, when the sizes, positioning intervals, etc. of the openings are varied, the weight balance of the disk is disrupted, forming regions that are lighter in weight than other parts and regions that are heavier in weight than other parts. Thus by selection of the sizes and positioning intervals of the openings, a heavy point, which is a portion that is relatively heavy in weight, can be formed at the desired position. Also, by attaching an air valve for inflating the tire at a position corresponding to the position of the heavy point thus formed, the checking of the heavy point position of the wheel is facilitated.
Furthermore with the abovementioned wheel, a plurality of openings may be formed at equal intervals in the circumferential direction of the disk and the opening areas of a part of the openings may be made smaller than the opening areas of other openings.
With this wheel, since a region in which openings that are smaller in diameter than other openings will be heavier by the amount corresponding to the differences in opening area, the heavy point of the wheel can be formed in the region in which the small-diameter openings were formed. Here, in the case where the difference in the sizes of the openings is small, the heavy point of the wheel can be adjusted without damaging the outer appearance.
Or with the above-described wheel, a plurality of openings may be formed at equal intervals in the circumferential direction of the disk and the distance between centers of a part of the adjacent openings may be made shorter than the distance between centers of other adjacent openings.
With this wheel, since a region in which openings with the longer distance between centers are formed will be heavier than other regions, the heavy point of the wheel can be positioned in the region in which openings with the longer distance between centers are formed.
Also with the above-described wheel, the openings may be formed at equal intervals along the circumference of a circle that is centered at a position that is decentered from the center of the disk.
With this wheel, since a region in which many openings are formed and a region in which few openings are formed can be formed in the disk by forming the openings along the circumference of a circle having the center at a position that is deviated from the center of the disk, the heavy point can be positioned in a region in which the number of openings formed is small.